A histological study of the accessory reproductive organs of female Loligo forbesi (Cephalopoda: Loliginidae)

In Loligo forbesi Steenstrup, the female reproductive system consists of the ovary and accessory reproductive organs which include the oviducal gland, the nidamental gland, the accessory nidamental gland and seminal receptacle. Histological studies were made on the accessory reproductive organs of female L. forbesi. The various changes observed during maturation are described and the functional significance discussed. The secretions produced by the oviducal gland and nidamental gland apparently form the egg coats. The seminal receptacle serves to store spermatozoa after mating. The function of the accessory nidamental gland is unknown.     

Sinohesione genitaliphora gen. et sp. n. (Polychaeta, Hesionidae), an interstitial annelid with unique dimorphous external genital organs

A new hesionid. Sinohesione genitaliphora gen. et sp. n., is described from intertidal sandy sediments of Hainan Island, China. It differs from hitherto known hesionids by the presence of external genital organs in both sexes. In the males there is one pair of sae-like appendages, each bearing a tube-shaped penis, on chaetiger 10. In the females the paired sae-shaped organs are situated on chaetiger 12. Reconstructions of semi- and ultrathin sections show that a long, heavily coiled sperm duct opens at the tip of each penis. The duct opens with a ciliated funnel into a seminal vesicle in chaetiger 9. Prominent gland cells surround the sperm duct for the most part. The female genital organs each have two openings; one of which leads to a blind ending seminal receptacle. The other is the external pore of a ciliated oviduct that originates as an open funnel in the coelom of chaetiger 10. The functional and phylogenetic significance of these structures is discussed.     

平疣桑椹石磺生殖系统结构及精子储存场所

雌雄同体贝类精子的储存和利用规律一直是国内外贝类生物学研究的难点之一,本文利用活体解剖、显微观察、组织切片和扫描电镜技术,综合研究了平疣桑椹石磺(Platevindex mortoni)的生殖系统及精子储存场所。结果显示,其生殖系统包括生殖器本部、雌性生殖部分和雄性生殖部分。生殖器本部由两性腺、两性输送管、蛋白腺、黏液腺、支囊组成;雌性生殖部分包括输卵管、受精囊、阴道,位于身体中后方体腔内;雄性生殖部分包括输精管、刺激器、阴茎、阴茎鞘和阴茎牵引肌,位于身体前端右侧体腔内;其阴茎有阴茎鞘,阴茎表面布满倒刺。平疣桑椹石磺阴茎为直线状,无雄性附属腺。未交配的性成熟个体支囊内充满细长精子,受精囊内无精子;而交配后充当雌性个体的支囊内均为细长的自体精子,受精囊内有大量活力较强的粗短精子,其支囊为自体精子的存储场所,而受精囊为异体精子的存储场所。其精子储运情况为:两性腺内精子成熟后暂存于支囊,交配时通过输精管运输至阴茎,由阴茎输送精子至对方的阴道,异体精子进入受精囊内存储待用。     

泥螺生殖系统的组织学

泥螺为雌雄同体。生殖系统包括交媾器和生殖器本部。交媾器包括刺激器、阴茎和摄护腺;生殖器本部主要包括两性腺、缠卵腺和蛋白腺。刺激器和阴茎都具有非常发达的肌肉组织,腔壁游离面具纤毛。阴茎腔壁为单层柱状细胞;摄护腺被膜为一层薄的肌纤维,里面具有许多分泌细胞;缠卵腺被膜为单层扁平上皮,下层为环肌,腺体组织由分泌小管构成。蛋白腺主要由皮质层和导管层组成,皮质层内充满了分泌细胞,导管层由许多分泌小管构成,管壁为柱状腺细胞。     

Spermiophagic activity in the female genital system of some species of terrestrial isopods (Crustacea,Halophilosciidae)

The females of some species of the family Halophilosciidae receive in the course of mating a quantity of sperm considerably redundant with respect to the number of eggs that can be fertilized; this is possible thanks to the peculiar morpho-functional organization that characterizes their genital system and that allows them to store the sperm not only in the great seminal receptacle but also within the ovary. While most of the sperm stay free in the lumen of the seminal receptacle, a part of those present in the ovary undergoes a process of capture by the follicular cells with consequent internalization within endocellular cavities. This process concerns exclusively the immotile tail, that characterizes the peculiar spermatozoon of the isopods and which is essentially of proteic nature. After their capture the sperm tails undergo a gradual process of digestion, which seems to be apparently realized without the intervention of lysosomes. The possible role of this spermiophagic activity might be to represent a significant trophic paternal investment aimed at improving the fitness of the female and of the offsprings.     

Ultrastructural Morphology of the Male and Female Genital Tracts of <Emphasis Type="Italic">Psoroptes</Emphasis> spp. (Acari: Astigmata: Psoroptidae)

The structure of the male and female genital systems of the astigmatid mite Psoroptes ovis (Hering) is described. The male genital system is composed of a paired testis, fused at its proximal part, two vasa deferentia, an ejaculatory duct, into which a single accessory gland opens, and a copulatory organ. The testis is characterized by a peripheric syncytial cell surrounding spermatogonia, spermatocytes, spermatids and spermatozoa which are distributed regularly in the gonad according to the sequence of spermatogenesis. The female genital system consists of a copulatory pore (the bursa copulatrix), a seminal receptacle, paired ovaries and oviducts, a glandular uterus and an ovipositor which leads to the oviporus. Ovaries are composed of somatic cells, germ cells and a central cell, with a multilobular nucleus, connected to oocytes by a stalk. Similarities with other astigmatic mites belonging to Psoroptidia and Acaridia are also discussed.     

Reproduction in the genus Limacina (Opisthobranchia: Thecosomata)

Reproductive mechanisms in the seven species of the thecosomatous pteropod genus Limacina are described and compared. All species are protandrous hermaphrodites. Five species– L. bulimoides, L. helicina, L. lesueuri, L. retroversa and L. trochiformis –have a similar reproductive anatomy in which the gonoduct leading from the gonad to the common genital pore functions as a seminal vesicle in the male and is elaborated into mucous and albumen glands in the female. The male system consists of a prostate gland and penis connected to the common genital pore by an external ciliary tract. All five species have a free-swimming veliger stage which hatches from free-floating egg masses. Limacina helicoides has the same reproductive anatomy but is ovoviviparous, with embryos retained in capsules in the mucous gland until they are juveniles of 50 mm in shell diameter. Limacina inflata lacks mucous and albumen glands and a penis; a spermatophore formed by the prostate gland is used in aphallic sperm transfer. This species exhibits brood protection with un-encapsulated embryos retained in the mantle cavity until they are released as veligers measuring 0067 mm in diameter. L. inflata is the most abundant of the seven species despite lowered fecundity; reasons for its ecological success are discussed.     

Ultrastructure of the male accessory ducts and prostate gland of Diclidophora merlangi (Monogenoidea)

The vas deferens, seminal vesicle, penis and common genital atrium of the monogenean, Diclidophora merlangi are lined by a very flat, lamellate epithelium. The structure is apparently syncytical, although nuclei or perikaryons have not been observed. The epithelium extends to just inside the gonopore where a septate desmosome marks the union with body tegument. There is minor regional variation in structure. The terminal portion of the seminal vesicle and the penis lumen are lined in part by the luminal cytoplasm of the prostate gland which surrounds this part of the reproductive tract. The prostate gland cells are synthetically active and produce a characteristic secretory body that is released either singly by exocytosis, involving membrane fusion, or in bulk via apocrine secretion. The secretion is acidophilic, PAS-positive and reactive for protein. The penis is sucker-like in structure and armed with a ring of 16 genital hooklets. Cilia have not been observed in any part of the male reproductive tract, and sense receptors are not apparent in the tegument surrounding the gonopore.     

Functional morphology of the copulatory system of box crabs with long second gonopods (Calappidae,Eubrachyura, Decapoda,Crustacea)

Male True Crabs use two pairs of gonopods to deliver mating products during copulation. Commonly, the second pair is shorter than the first pair, and most research to date has focused on species with short second gonopods. We investigated male and female copulatory organs in Calappula saussurei and Calappa pelii, two species of box crabs (Calappidae) with second gonopods which are longer than the first pair. Scanning electron microscopy and histological cross sectioning show that the female copulatory system is unique in several aspects: the genital duct is part concave and part simple type. The seminal receptacle is divided into two chambers, a ventral chamber of ectodermal and mesodermal origin, and a dorsal chamber of ectodermal origin. This dorsal chamber is the location of spermatophore reception during copulation. A sperm plug closes the dorsal chamber off. We propose that long second gonopods deliver male mating products directly into the dorsal chamber. To date, spermatophore reception has been associated with the mesodermal tissue of the seminal receptacle. The copulatory system of box crabs with long second gonopods shows novel deviations from this general pattern. J. Morphol. 276:77–89, 2015. © 2014 Wiley Periodicals, Inc.     

耳河螺生殖器官和精子的形态学研究

耳河螺「Ｒｉｖｕｌａｒｉａ ａｕｒｉｃｕｌａｔａ （Ｍａｒｔｅｎｓ）」为雌雄异体。雄性生殖器官由精巢,输精小管,贮精囊,输精管,前列腺和阴茎组成。精巢内有精子,精子有典型精子和非典型精子两种。扫描电镜下,典型精子头部呈螺旋状,尾端只有一根较粗壮;非典型精子头部和中部为棒状,尾部呈扫帚状,由８－１５根鞭毛组成。     

多肠目薄背涡虫生殖系统结构及一氧化氮合酶组化研究

运用常规组织学方法和NADPH-d组织化学方法,研究了薄背涡虫 Notoplana humilis 生殖系统的组织结构和一氧化氮合酶的分布.其雄性生殖系统包括精巢、储精囊、阴茎、雄性生殖孔,精巢壁由一薄层薄膜组成,每个精巢内都含有不同发育时期的雄性生殖细胞,且精子发育无明显同步性;储精囊呈螺旋状排列在雄性生殖孔附近,囊壁由单层扁平上皮组成;阴茎为粗大的球形,外壁由柱状上皮细胞和数层肌细胞组成.雌性生殖系统包括输卵管、生殖腔、雌性生殖孔和受精囊,但不形成集中的卵巢和卵黄腺.雌雄生殖孔、生殖腔、受精囊、阴茎等部位呈NADPH-d强阳性反应.     

Functional morphology of the sperm-containing chambers of the sea slug Okenia polycerelloides in the context of sexual selection

Sea slugs are interesting models to study post-copulatory sexual selection in simultaneous hermaphrodites due to the enormous variation of their reproductive systems. However, the knowledge of the functional morphology of their reproductive system is limited to few species, and it is rarely discussed in the context of sexual selection theory. In this study, we investigated the functional morphology of the sperm-containing chambers (i.e., ampulla, seminal receptacle, and bursa copulatrix) of the reproductive system of Okenia polycerelloides (Ortea & Bouchet, 1983), based on light, confocal, and electron microscopy. Although the morphology of the ampulla is similar to other species, indicating that it is a site for autosperm storage, we found some sperm facing the ampullar epithelium, a feature commonly regarded as characteristic of the seminal receptacle of sea slugs. The seminal receptacle of O. polycerelloides showed secretory activity and contained sperm with distribution and orientation suggestive of stratification of allosperm from distinct mating events, a feature that would affect sperm competition. The bursa copulatrix had epithelial cells with secretory and absorptive characteristics, and contained degraded sperm and yolk granules within its lumen. Comparative analyses of the contents of each organ demonstrated that sperm digestion occurs in the bursa copulatrix and affects sperm heads first, changing their morphology from slender and curved to shorter and ellipsoid before complete lysis. Although digestion and absorption of surplus sperm are currently the main hypothesized functions for the bursa copulatrix, its role in cryptic female choice should not be ruled out. The close structural connection between the seminal receptacle and bursa copulatrix, as well as their muscular walls, would enable control over the fate of the sperm received in each mating event, that is, storage or digestion.     

Sperm transfer and mating in Ricinoides hanseni (Ricinulei: Arachnida)

Ricinuleid reproduction involves indirect sperm transfer using the highly modified distal podomeres of the third legs of the male. This is homologous with the apparatus and technique used by male spiders, which possess elaborate pedipalps. The interpretation of the method of sperm transfer is based upon morphological studies of the male's third legs and the female's genital atrium and the behaviour of males during mating. The male charges the emboli of his modified leg tarsi with sperm from his penis. After climbing on to the back of a receptive female he delicately and precisely places a modified tarsus in the genital atrium of the female. A series of lobes on the tip of part of the modified tarsus fit into a number of vesicular evaginations of the female's genital atrium. The lobes form part of the mechanism which provides a firm attachment of the male's tarsal elements with the female's genital atrium during sperm transfer. A tubular element of the modified tarsus fits into a spermatheca of the female. Sperm and seminal fluid are then injected from the male's embolus into the female's spermatheca.     

A hypothesis about the origin of sperm storage in the Eubrachyura, the effects of seminal receptacle structure on mating strategies and the evolution of crab diversity: How did a race to be first become a race to be last?

The origins and evolution of sperm storage in Brachyura are enigmatic: sperm is either stored in seminal receptacles, accessible via the vulvae on the sixth thoracic sternite, or in spermathecae at the border between the seventh and eighth sternites. Crabs with spermathecae are collectively referred to as “podotremes” while crabs with seminal receptacles belong to the Eubrachyura. The position of gonopores is the primary basis for subdividing the Eurachyura into the Heterotremata (female vulvae + males with coxal gonopores) and Thoracotremata (female vulvae + males with sternal gonopores). We present a hypothesis about the evolution of seminal receptacles in eubrachyuran female crabs and argue that the sternal gonopore has been internalized into chitin-lined seminal receptacles and the vulva is in fact a secondary aperture. The loss of some or all of the ancestral chitinous seminal receptacle lining was linked to ventral migration of the oviduct connection. Male and female strategies are to maximize gamete fertilization. The most important variable for females is sperm supply, enhanced by long-term storage made possible by the seminal receptacle. To maximize their fertilization rates males must adapt to the structure of the seminal receptacle to ensure that their sperm are close to the oviduct entrance. The major evolutionary impetus for female mating strategies was derived from the consequences of better sperm conservation and the structure of the seminal receptacle. The advantages were all to the females because their promiscuity and sperm storage allowed them to produce more genetically variable offspring, thereby enhancing variation upon which natural selection could act. We extend our arguments to Brachyura as a whole and offer a unifying explanation of the evolution of seminal receptacles, comparing them with the spermathecae found in “Podotremata”: they were independent solutions to the same problem: maintaining sperm supply during evolutionary carcinization.Explanation of eubrachyuran mating strategies requires analysis of the mating–moulting link, indeterminate vs. determinate growth format and seminal receptacle structure. Two alternatives for each of these characters means that there are eight possible outcomes. Six of these outcomes have been realized, which we term Portunoid, Majoid, Eriphoid, Xanthoid, Cancroid, and Grapsoid–Ocypodoid strategies, respectively. Mapping these characters on to a workable phylogeny (wherein some changes to the seminal receptacle + moulting–mating links are assumed to have occurred more than once) produces the following relationships: Portunoids + Majoids are a sister group to the rest of the Eubrachyura, which fall into two sister groups, Eriphoids + Xanthoids and Cancroids + Grapsoid–Ocypodoids and the “Podotremata” is sister group to all the Eubrachyura. We conclude that what began as a race to be the first to mate was turned on its head to become a race to be last, by the evolutionary changes to the seminal receptacle. Eubrachyuran females were advantaged by greater reproductive autonomy, more opportunity to mate with other males, resulting in more genetically variable progeny and leading to the evolution of much greater taxonomic diversity compared to “podotremes”.     

Sperm transfer during mating in the pharaoh's ant, Monomorium pharaonis

Abstract.  Sperm transfer in the pharaoh's ant Monomorium pharaonis (L.) is studied by making longitudinal sections through the gasters of mating pairs fixed in copula. Sperm is transferred inside a spermatophore similar to those found in two other ants, Diacamma sp. from Japan and Carebara vidua . Sharp teeth-ridges are present on the penis valves and, during copulation, these teeth make contact with a thick and soft cuticular layer covering the bursa copulatrix. This ensures an attachment long enough for the successful transfer of the spermatophore to the right position inside the female oviduct. The thick cuticle also protects the queen from serious damage by the male's sharp claspers. After a first successful copulation, sperm is still present inside the male's seminal vesicles, suggesting that males can mate multiply. Additional experiments, where single, initially virgin males are presented to several virgin females, confirm this.     

A new interpretation of the female genitalia in Macrocyclops albidus (Copepoda, Cyclopidae)

The female genital structures of Macrocyclops albidus (Cyclopidae, Eucyclopinae) were studied using light and electron microscopy. The results confirm that the exterior genital area shows only a copulatory pore, located anteromedially on the ventral face of the genital double-somite, and paired gonopores (not directly visible), situated laterally under the P6 plates. An internal seminal receptacle, composed of several parts, is connected to the gonopores by ventro-lateral cuticular extensions or seminal ducts. The lateral site of communication shows a complex set of connections between the seminal receptacle and the oviducts (via the egg-laying ducts). The structure until now designated as ‘transverse ducts’, visible by transparency on the ventral face, is in fact constituted of internal cuticular thickenings resulting of the fusion of the 6th thoracic somite and the 1st abdominal somite forming the genital double-somite and appearing externally as a part of the suture line; the term ‘suture cord’ is proposed to designate it. The functioning of the system is explained.     

Ultrastructural aspects of the oesophageal and reproductive systems of the equine parasite Strongylus vulgaris

The ultrastructure of the dorsal oesophageal gland ampulla and its relationship with the oesophagus, oesophageal ultrastructure, and control mechanisms in oesophageal activity were studied. Terminal ducts of the sub-ventral glands open through the oesophageal crown at the base of the buccal cavity. The terminal duct of the dorsal oesophageal gland running through the dorsal gutter opens to the exterior at the rim 'groove' of the buccal capsule. The posterior oesophageal region is clavate and the cuticle of the lumen folds to form outlet valves, 'valvulae'. An inconspicuous oesophago-intestinal valve (three lobes) connects oesophagus and intestine and is visualized in the open and shut position. In the female reproductive tract, with the exception of the uterus, the cells lie on a thick, irregular (convoluted) basal lamina. The apical plasma membrane of the uterus, and seminal receptacle, extend into the lumen by microvilli-like projections with which spermatozoa make intimate contact. The lumen of the uterus is filled with oocytes, fertilized and unfertilized. Testicular cells have two parts linked by a rachis. Spermatocytes are elongated with a large nucleus, distinct nuclear membrane, and many granules. The apical membrane of the rachis forms long microvilli-like projections with balloon-like tips. The amoeboid spermatozoa contain membrane specializations, a nucleus devoid of a membrane, and are enclosed by a pseudopodial-like extension.     

Ultrastructural organization of the genital tracts in amphigonic females of Euceraphis betulae Koch (Aphididae: Calaphidinae)

The ultrastructure of the genital tracts in amphigonic females of Aphidoidea is described for the first time, using Euceraphis betulae Koch (Aphididae: Calaphidinae) as a representative. The female reproductive apparatus consists of two ovaries, each one with three/four meroistic telotrophic ovarioles; two sac‐like accessory glands lie laterally to a sac‐like seminal receptacle, opening into the dorso‐medial part of the common oviduct by means of a spermathecal duct. A marked secretory activity takes place in the epithelial cells of all the investigated tracts as shown by ultrastructural observation of many organelles involved in this process. No evident golgian area was observed in the cytoplasm of these cells. Extensive smooth endoplasmic reticulum, whose probable role is here discussed, was observed in epithelial cells of the wall of the accessory gland. Spermathecal duct and seminal receptacle had peculiar features that could be related to different secretory activities carried out by these two parts of the spermatheca.